The present invention relates generally to gas handling devices, and more particularly, relates to gas handling devices that are capable of supplying, evacuating and purging a process gas and are also capable of handling multiple process gases in a single gas handling device.
In a semiconductor manufacturing process, a variety of process tools are utilized, such as steppers, etchers and the like, each of which requires a constant supply of process gases in order to produce semiconductor devices of uniform quality. A tool may require multiple supply lines of process gases, such as nitrogen, oxygen, hydrogen, boron trichloride, fluorine, silicon tetrafluoride, silane, argon, etc. Many process gases are flammable, toxic and/or pyrophoric and therefore require special precautions in order to be utilized safely.
A conventional gas handling device, also known as a gas isolation box, typically includes a plurality of gas handling units, also known as gas sticks or gas isolation assemblies. For the sake of simplicity, the gas handling device will be referred to hereafter as a gas isolation box or GIB and the gas handling units will be referred to hereafter as gas sticks.
Each gas stick may have various stop valves, mass flow controllers, pressure transducers, filters, etc. which are coupled to each other by various types of union fittings as is well known to those skilled in the art. The gas sticks are also coupled to a gas inlet which provides process gas from a remote gas supply and to a gas outlet which leads to a tool, sometimes remotely located. The components of each gas stick are rigidly fastened to a mounting block. The components of each gas stick so mounted on the mounting block are then positioned within an enclosure to make up the GIB. For safety reasons, all tubing coming to the GIB is welded to the GIB to avoid leaks.
Various GIBs are illustrated in the prior art including those shown in Barr et al. U.S. Pat. No. 5,732,744, Seaman et al. U.S. Pat. No. 5,915,414, and Johnson U.S. Pat. No. 6,076,543, the disclosures of which are incorporated by reference herein. As disclosed in Seaman et al., a plurality of gas sticks are located in an enclosure. Purge gas is supplied from a manifold and is manually controlled external to the GIB.
Several disadvantages are apparent from the prior art. First, some functions of the GIB, such as purging, are not contained within the GIB so extra room around the GIB need be made to account for the external functions. Second, only one process gas is supplied to a given GIB. Thus, there needs to be multiple GIBs to accommodate multiple process gases. Third, conventional GIBs are manually controlled which necessarily requires an operator to be available to attend to the GIB. Fourth, the functions present in conventional GIBs are limited.
It would be desirable to have a GIB which resolves the difficulties inherent in conventional GIBs.
Accordingly, it is a purpose of the present invention to have all functions of the GIB contained within the GIB.
It is another purpose of the present invention to have a GIB that can handle multiple process gases at the same time.
It is yet another purpose of the present invention to have a GIB which is controlled pneumatically and/or electronically.
It is still another purpose of the present invention to have a GIB which can handle multiple functions of supply, evacuate and purge of a process gas.
These and other purposes of the present invention will become more apparent after referring to the following description of the invention considered in conjunction with the accompanying drawings.
The purposes of the invention have been achieved by providing, according to a first aspect of the invention a gas stick comprising:
a process gas section comprising a first process gas inlet valve for gating the flow of a process gas into the gas stick;
a purge gas section comprising a purge valve for gating the flow of a purge gas into the gas stick; and
an evacuation section comprising a first evacuation valve for gating the exiting of a process gas or a purge gas from the gas stick, a bleed valve which in a closed position allows process gas to bleed through the bleed valve and in an open position allows purge gas to freely flow through the bleed valve, and a vacuum generator module which pulls a vacuum to evacuate a purge gas or any remaining process gas in the gas stick or the tool through the first evacuation valve and the bleed valve and out from the gas stick to an exhaust stream.
According to a second aspect of the invention, there is provided a gas isolation box comprising:
an enclosure;
a plurality of gas sticks contained within the enclosure, each gas stick comprising:
a process gas section comprising a first process gas inlet valve for gating the flow of a process gas into the gas stick;
a purge gas section comprising a purge valve for gating the flow of a purge gas into the gas stick; and
an evacuation section comprising a first evacuation valve for gating the exiting of a process gas or a purge gas from the gas stick, a bleed valve which in a closed position allows process gas to bleed through the bleed valve and in an open position allows purge gas to freely flow through the bleed valve, and a vacuum generator module which pulls a vacuum to evacuate a purge gas or any remaining process gas in the gas stick or the tool through the first evacuation valve and the bleed valve and out from the gas stick to an exhaust stream.